"We all know how the blueprints achievement tracker messes up in co-op, but I have a solution that worked for me to get the achievement. After I beat the game, my partner and I had found/unlocked 98 of the 101 weapon blueprints and 8 of the 11 vehicle blueprints (so 106 total). I never got the achievement for finding 50, nor the one for 100. My tracker said I collected only 48. I loaded up my single player save by chapter selecting Chapter 1, and immediately, my 50 blueprint achievement (Engineer) unlocked. The tracker then showed 51%. I then tried various methods to no avail, but I discovered that if you keep loading up chapters through Chapter Select (I recommend doing this after you beat the game so you don't lose story progress), the tracker will keep increasing. It doesn't matter which chapters you choose, any will work. Everytime I loaded a chapter, it would increase between 4 and 8%. I did this until it finally unlocked upon my last load when I was at 99% and did one last chapter select. I really hope this helps! "

Let me know if this works for you guys too; If it does I'll keep the solution up - If not I'll remove it.

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